The present invention relates to intercalation compounds for use as electrodes for batteries, and in particular metal ion doped lithium manganese oxide compositions, articles manufactured with such compositions, and batteries including electrodes formed from such compositions.
The present inventors, or at least some of them, have previously provided an extensive review of the background behind the use of lithium intercalation compounds in rechargeable batteries, international application no. PCT/US97/18839, filed Oct. 10, 1997 by Mayes, et al, entitled POLYMER ELECTROLYTE, INTERCALATION COMPOUNDS AND ELECTRODES FOR BATTERIES published as WO 98/16960 incorporated herein by reference. That patent specification includes examples of compositions of the formula LixMyNzO2, wherein M and N are each a metal atom or main group element, and methods for synthesizing such compositions which are demonstrated to have improved electrochemical properties. WO 98/16960, at least insofar as it relates to intercalation compounds, is incorporated herein by reference.
The present inventors have continued to investigate lithium intercalation compounds to identify new compounds with further improved properties for use in batteries.
Thus, it is an object of the present invention to provide lithium intercalation compounds, and methods of their production, which have improved properties for use in batteries.
Other objects of the invention may become apparent from the following description which is given by way of example only and with reference to specific examples.
According to one aspect of the present invention, there is provided a composition including particulate metal oxide material including a plurality of particles of multicomponent metal oxide, each including an oxide core of at least first and second metals in a first ratio, and each including a surface coating of metal oxide or hydroxide that does not include the first and second metals in the first ratio formed by segregation of at least one of the first and second metals from the core.
According to a further aspect of the present invention there is provided a composition including particulate metal oxide material including particles of a multicomponent metal oxide, each including an oxide core of at least first and second metals in a first ratio, and each including a surface coating of metal oxide or hydroxide that does include the first and second metals in the first ratio formed by application of an auxiliary metal oxide or hydroxide to the particles, and the cores comprise LixMyNzO2, wherein M is a metal atom or a main group element, N is a metal atom or a main group element, each of x, y and z is a number from about 0 to about 1, y and z are such that a formal charge on a MyNz portion of the compound is (4xe2x88x92x), and having a charging voltage of at least about 2.5V.
According to a further aspect of the present invention there is provided an article including particles as referred to in the previous two paragraphs, wherein the particles are ion intercalation particles at least some of which are in contact with an electrically-conductive material and an ionically-conductive material.
According to a further aspect of the present invention there is provided a method including allowing a first component of a multicomponent oxide based intercalation compound to segregate from a plurality of particles of the compound disproportionately to the surfaces of the plurality of particles to form protective layers of the first component on the particles; exposing the plurality of the particles to chemically degrading conditions; and allowing the layers to shield the particles from the chemically degrading conditions such that the particles exhibit robustness, under the conditions, greater than identical particles absent the layers.
According to a further aspect of the present invention there is provided a multicomponent oxide useable as a lithium intercalation material including a multiphase oxide core and a surface layer of one material, which is a component of the multiphase oxide core, that protects the underlying intercalation material from chemical dissolution or reaction.
According to a further aspect of the present invention there is provided a multicomponent oxide into which lithium can be reversibly intercalated, and in which part or all of one constituent of the multicomponent oxide spontaneously forms a surface layer which protects the underlying intercalation compound against chemical dissolution or reaction.
According to a further aspect of the present invention there is provided a composition of the formula LixAlyMn1xe2x88x92yO2 structure, wherein y is non zero.
According to a further aspect of the present invention there is provided an electrode for a primary lithium battery having at least one component, at least one component having a LixAlyMn1xe2x88x92yO2 orthorhombic structure, wherein y is non zero.
According to a further aspect, the composite intercalation material comprises at least two compounds. At least one compound has an orthorhombic structure LixAlyMn1xe2x88x92yO2, where y is nonzero.
According to a further aspect, a composite intercalation material comprising at least two compounds has at least one compound, which upon electrochemical cycling, has a transformation in the voltage vs. capacity curve from a single plateau at about 4 V to two plateaus at about 4 V and 3 V respectively.
According to a further aspect, a composite intercalation material comprising at least two compounds has at least one compound having a discharge capacity of at least about 100 mAh/g over the voltage range 2.0-4.4 V, and an energy density of at least about 400 Wh/kg after 50 cycles.
According to a further aspect, a composite intercalation compound containing at least two individual intercalation compounds is provided where each compound has a different lithium chemical diffusion rate and a voltage vs. capacity profile that varies more continuously than the voltage vs. capacity profile of any noncomposite intercalation compound.
According to a further aspect, a composite intercalation compound containing at least two individual intercalation compounds is provided where each compound has a different particle size and a voltage vs. capacity profile that varies more continuously than the voltage vs. capacity profile of any noncomposite intercalation compound.